1. Field of the Invention
The invention relates to a ceramic heater, a method of producing the same and an article having a metal member.
2. Related Art Statement
In a semiconductor producing system, ceramic heaters have been applied to heat a wafer so as to deposit a semiconductor thin film on the wafer from gaseous raw materials such as silane gas by means of thermal CVD or the like. For example, Japanese Patent publication P2000-68, 038A disclosed this kind of ceramic heater. The heater has a substrate made of a nitride ceramics and a heat resistor made of, for example, tungsten. A tungsten silicide and tungsten carbide layers are formed in the heat resistor during the sintering process of the ceramic substrate.
Japanese Patent publication 11-251, 039A discloses a heater having a substrate made of aluminum nitride ceramics and a heat resistor embedded therein. In the heater, the resistor is composed of, for example, tungsten and tungsten carbide. Further in the heater, a ratio (I2/I1) of a main peak strength of tungsten (I1) to that of tungsten carbide (I2) is adjusted to a value between 0.9 to 6.0. It is thus made possible to reduce the resistance-temperature system.